Description

• Add secret part in NubeConfig (SecretConfig similar to AppConfig)
• Provide reference variable like: @<part>.<var_name> and in "__secret__" has @secret.<var_name> key. For example:

  {
    "__app__": {
      "password": "@secret.abc"
    },
    "__secret__": {
      "@abc": "<actual_value>"
    }
  }

DOD

• If ref_var not found, just return and keep it as it is
• Exclude secret config in logging
• Work well System properties and Environment variables
• Never show secret in REST response of CREATE/UPDATE/PATCH/GET/GET_LIST service/module
• Introduce specific endpoint for GET/PATCH/UPDATE secret config /modules/<module_id>/secret, /services/<service_id>/secret
• Provide inject secret method in SharedData to invoke manually when needed